The present invention relates to complex reflectors, and their fabrication, for use in applications requiring unusual shapes, typically other than a single conic section, while providing image forming optical effects for viewing or projecting images correctly and in focus or intensity profiles in a desired pattern.
One application of such mirror is in the field of rear view automotive mirrors. It is desirable, and to some extent required by regulation, to be able to see a wide angle of view in the rear view. This is often accomplished by the provision of a convex rear view reflector. At the same time it is of advantage to be able to see certain portions of the rear field of view with nearly unity magnification, while wider views are needed as well so that car positions in all rear locations affecting passing and lane change decisions are easily known. To achieve these goals mirrors of variable magnification have been used. This is accomplished either by affixing a convex mirror at some location on a unity magnification mirror, or by varying the magnification across the mirror width. The former produces two different views and it is difficult for a driver to assimilate both instantaneously, keeping in mind the relative magnifications of each. The latter causes one eye of the human observer to view the scene at a different magnification than the other eye. The result is that the two see different size images and superposition of them in the mind is far from perfect, creating an unclear view. If it is additionally desired to relay the image to the interior of the vehicle for viewing at an interior display, such as adjacent the interior rear view mirror, the optical problems become severe.
In addition, the definition of the shape for a variable magnification mirror is not readily achieved since the mirror does not fall into one of the traditional conic section shapes. This makes it difficult and expensive to produce such mirrors. Accordingly, where mirrors are desired with odd shapes, for example for headlight lamp reflectors that accommodate a bulb of finite dimensions, and asymmetrical targets the trend is to adopt only one shape, limiting design flexibility.
In headlamp reflector design it is further necessary to project an illumination beam in a required intensity pattern. The generation of a single reflector to accomplish this in the past has not been practical, requiring instead the use of a conventional shape, such as parabaloid, in combination with a complex refractor pattern in the lens.
Other applications where special shapes could be used to advantage include off-axis overhead projectors where tilt compensation would permit projection of a properly proportioned image using a single reflector. Projection of TV images or of information in a head up display could also profit by the use of such mirrors. Indirect interior and exterior lighting would also benefit by the use of such reflectors. Many other applications require complex optical or electromagnetic transformations.